JPS61178411A - Production of granular active carbon - Google Patents

Abstract

PURPOSE:In obtaining granular active carbon for desulfurization by molding a blend of non-caking coal and a binder, carbonizing and activating it, to produce granular active carbon having improved adsorption ability and mechanical strength, by adding a specific binding agent to the binder. CONSTITUTION:Non-caking coal such as lignite, brown coal, etc., is blended with a binder such as coal tar, pulp waste liquor, etc., and, if necessary, an additive, kneaded, molded, carbonized, and activated to give granular active carbon for desulfurization. In the operation, a specific binding agent in a pitch state, having >=150 deg.C softening point and 0.6-1.0 H/C, obtained by heat-treating petroleum heavy oil, is added as part of the binder. The blending ratio of the non-caking coal in the blend of the non-caking coal and the binder is preferably about 70-90wt%, and the blending ratio of the specific binding agent is preferably >=about 4wt%. The use of a specific binding agent in this way can reduce cost of flue-gas desulfurization.

Description

[Detailed Description of the Invention] Industrial Application Field The present invention relates to a method for producing activated carbon for desulfurization using coal as a main raw material, and in particular, a method for producing activated carbon for desulfurization that has excellent adsorption ability and mechanical strength. in between.

BACKGROUND OF THE INVENTION Various methods have been proposed as flue gas desulfurization methods, but in the case of coal-fired power plants, etc., the dry method, which requires less wastewater and water consumption, has been attracting attention due to its location and other factors.

Moreover, instead of the method of recovering gypsum as a by-product, a method of recovering elemental sulfur has become the mainstream of the dry method.

The mainstream dry method is a method in which 502 in coal combustion exhaust gas is adsorbed on activated carbon, which is a desulfurization agent, and the activated carbon that has adsorbed SO2 is regenerated by thermal desorption and recycled. Therefore, the activated carbon inevitably circulates through the adsorption tower and the thermal desorption/regeneration tower, and is worn out during the circulation process. The size of the activated carbon is 5 to 5, taking into consideration ventilation pressure loss in the adsorption tower, etc.
Although 10 mm diameter activated carbon is mainly used, the activated carbon that is pulverized during the circulation process increases ventilation pressure loss in the adsorption tower. Therefore, it is necessary to classify and remove them in the circulation process. Furthermore, during thermal desorption, part of the carbon in the activated carbon is consumed when the adsorbed SO2 is released.

That is, activated carbon for desulfurization is a consumable item, and in the desulfurization process, it is necessary to replenish the circulation system with activated carbon in an amount equal to the amount consumed. For this reason, when the amount of wear is large, running costs increase, which in turn affects desulfurization costs. Furthermore, as the scale of thermal power plants increases, a large amount of activated carbon is also required. For this reason, there is a demand for activated carbon for desulfurization that is inexpensive, uniform in size, and has excellent adsorption capacity as well as mechanical strength such as impact strength and abrasion resistance.

In order to obtain such activated carbon, it is a good idea to manufacture granular activated carbon using coal as the main raw material, which is inexpensive and has a stable supply. If so, the mechanical strength will decrease, and conversely, if the mechanical strength is increased, the adsorption capacity will generally decrease.

For example, in a method for manufacturing a carbon material for desulfurization by molding a mixture of non-caking coal, caking coal, and a binder, and carbonizing the resulting molded coal in a rotary kiln, oxygen
1 kg of briquette coal is fed to a rotary kiln with heating gas containing 10% by volume and 20-80% by volume of water vapor.
1~1ONTr per hit? /hr to the rotary kiln, and the gas phase temperature at the inlet end of the rotary kiln is 450 to 650°C, and the gas phase temperature at the outlet end is 850 to 650°C.
A method for producing a carbon material for desulfurization characterized by maintaining the temperature at 00 to 1000°C (Japanese Unexamined Patent Publication No. 57-129813), or grinding lignite or subbituminous coal to 500μ or less and having a moisture content of 10 to 20 wt%. After drying as described above, 0.3 to 2.5 wt% of the lignite, subbituminous coal or mixture thereof.
It is characterized by adding an inorganic binder of 5 to 15+wmφ and granulating it to a size of 5 to 15+wmφ, and then carbonizing it in an inert gas or combustion gas at a temperature of 700 to 700°C and a temperature increase of 1 to 5°C/min. A number of proposals have been made, such as a method for producing an adsorbent (Japanese Patent Laid-Open No. 100123/1983), but these are not necessarily satisfactory.

Problems to be Solved This invention uses coal as the main raw material and has high mechanical strength.
Furthermore, the present invention provides a method for producing granular activated carbon for desulfurization that has excellent adsorption ability.

Means for Solving the Problems This invention involves blending a binder with non-caking coal, adding necessary additives as the case may be, kneading it, molding the resulting kneaded product, and then carbonizing and activating it. In a method for producing granular activated carbon for desulfurization, a softening point of 150° C. or higher obtained by heat treating petroleum heavy oil as part of the binder, H/Co, 6
This is a method for producing granular activated carbon characterized by adding a special binder of 1.0 to 1.0.

Function The non-caking coal used in this invention includes one or more of non-caking lignite, lignite, subbituminous coal, and anthracite. In particular, preferable results are obtained when lignite or subbituminous coal having an average reflectance (R) of 0.3 to 0.8 is used.

In addition, the special binder used as part of the binder is obtained by thermally decomposing heavy oil such as petroleum-based vacuum distillation residue oil, and has a softening point of 150°C or higher and an H/C of 0.6 to 1. 0.0, preferably 0.7 to 0.9 pitch material is used.

This special binder has a higher hydrogen content than normal coal tar pitch, but because of its large molecular weight, it has good reactivity with coal, even though it has a high carbonization yield during carbonization. It melts with coal and forms a strong carbide.

These non-caking coals and special caking agents are finely pulverized after or before blending, but the degree of pulverization is 100% in total.
It is preferable to set it to s+esh or less.

After pulverization, a special binder and a commonly used molding binder such as coal tar or valve waste liquid are used as binders, and non-caking coal is blended with this, and if necessary, additions are made to facilitate molding. The mixture is thoroughly kneaded using a high-speed kneader such as Kneader 1. The appropriate blending ratio of non-caking coal in the blend of non-caking coal and binder varies depending on the brand of non-caking coal, but is usually 60% or more, preferably 70 to 90%.

Further, the blending ratio of the special binder is preferably 4% or more. The simplest example of an additive that facilitates molding is water.

The kneaded product is formed using a briquette machine, an extrusion molding machine, etc., and is preferably 3 to 15 fflls in diameter.
Shape into an almond shape, pillow shape, cylinder shape, etc. of ~10 m. The strength of the molded product is such that the abrasion strength and crushing strength, which will be described later, are respectively 70% or more and 0.2 kg/P or more, preferably 80% or more and 1.0 kg/P or more.

Carbonization activation of the molded product is carried out in a transfer state or a fluidized state using a heating furnace such as an internal heating type or external heating type rotary kiln or a rolling kiln. Carbonization and activation may be carried out in the same heating furnace, or may be carried out in separate carbonization and activation furnaces. In the carbonization process, the final carbonization temperature is 600 to 1000 in a gas atmosphere such as nitrogen gas or combustion exhaust gas.
The heating rate was 100°C/100°C until around 400°C.
If the temperature is less than 1 minute, there will be no welding or expansion of the molded product. In the activation process, the temperature is 600 to 1000°C in a gas atmosphere such as nitrogen gas containing oxidizing gases such as oxygen and water vapor, and combustion exhaust gas.
By holding for 30 minutes to 10 hours, it is possible to obtain granular activated carbon with excellent adsorption ability and high mechanical strength.

Example 1 Non-caking coal (VM=30.0%, C5N=1.4Ro=0
．． 75) and a special binder with the properties shown in Table 1, each was pulverized with an atomizer to a total amount of 100 mesh or less, and then
Non-caking coal, special binder, and coal tar were blended in the blending ratio shown in Table 2, an appropriate amount of water was added, and the mixture was kneaded in a kneader. This kneaded product was molded using a disc pelleter to obtain a cylindrical molded product with a diameter of 5III11 and a length of 6 to 121 Wm. This molded product was carbonized in an inert atmosphere at a rate of 10°C/min to 850°C using a rotary kiln, and then steam activated at 850°C for 3 hours using nitrogen gas containing 57vo 1% of water vapor. Granular activated carbon having the properties shown in Table 2 was obtained.

In addition, SO2 adsorption capacity is SO2, 2vol%, H2O,
Synthesis gas containing 10vol%, 02.6vol%, and the balance N2 was brought into contact with granular activated carbon at 100°C for 3 hours to adsorb S02, and measurements were taken. Abrasion strength is JIS-M-8801
20g to the drum tester used for loga index measurement as described in
After charging granular activated carbon and rotating it 1000 times,
The material was sieved using a s+esh sieve, and the weight percentage on the sieve was defined as the abrasion strength. For the crushing strength, 30 pieces of granular activated carbon were arbitrarily taken out from the sample, and the crushing strength of each grain was measured using a Mizuya hardness tester, and the crushing strength was determined as the average value of the 30 pieces.

As a comparative example, the same test was conducted on granular activated carbon produced under the same conditions as above, except that coal tar was used as the binder, and soft pitch with a softening point of 30° C. and hard pitch with a softening point of 110° C. were used. The results are shown in Table 2.

The softening point was measured by the flow tester method for special binders, and by the ring and ball method for soft pitch and hard pitch.

Table 2 As shown in Table 2, the granular activated carbon of the present invention containing a special binder in the binder has high mechanical strength and SO2 adsorption ability compared to conventional coal tar pitch etc. as a binder. Approximately 30mg5 O2/compared to activated carbon
It is higher than g-AC.

Furthermore, even if the proportion of the special binder in the binder is greatly changed from 20 to 55 wt%, as shown in Table 2, granular activated carbon can withstand sufficient use, and when manufacturing activated carbon, composition control is extremely important. It's easy.

Note that in this example, the ratio of non-caking coal to no(inder) was set to 80:20, but this ratio should be optimal depending on the brand of non-caking coal used. The proportion is not limited.

Effects of the Invention As described above, according to the present invention, )
By blending a special binder with a temperature of ℃ or higher and H/Co of 6 to 1.0, it is possible to obtain granular activated carbon for desulfurization with excellent adsorption ability and mechanical strength, which helps reduce the cost of flue gas desulfurization. There is a lot to contribute.

Claims (1)

[Claims] In a method of manufacturing granular activated carbon for desulfurization by blending a binder with non-caking coal, adding necessary additives in some cases and kneading, molding the obtained kneaded product, and then carbonizing and activating it, A method for producing granular activated carbon, which comprises adding, as part of the binder, a special binder obtained by heat-treating petroleum-based heavy oil and having a softening point of 150° C. or more and an H/C of 0.6 to 1.0.